Abstract

In current G4M algorithm of forest management the amount of logging, primarily depends on wood demand However, the wood demand and logging do not have distinguished assortment structure of wood.

Inadequate representation of the main groups of the assortments reduces the reliability of simulationresults regarding the amount of biomass in the forests, emissions of carbon dioxide and amount of available wood for future harvests. To deal with this inaccracy we improve the existing algorithm of forest management to take into account assortment structure of modeled logging in G4M. We test the improved algorithm uing Ukraine as a case study.

The assortments are aggregated into two categories: 1) saw logs and veneer logs (SVL) and 2) other asortments of wood. A part of SVL in harvested wood in Ukraine is quite high - 51%. Requirements of standards regarding minimum diameter and height of SVL ae rather strict, while, for example, the requirements for pulpwood are more flexible. Wood suitable for SVL can be used for pulpwood, but not vice versa. Terefore, in the improved algorithm the assortments which have higher diameter and cannot be substituted by another assortment are in the first group, and the ther assortments are in the second group. Such grouping of assortments also agrees with GLOBIOM model that usually provides wood demand projections for G4M.

The improved algorithm deals with wood demand divided between SVL and other wood assortments. Conventonally, there are two blocks in the algorithm. The first block corresponds to the standard G4M algorithm with the only exception, now it estimates alowable amount of harvested SVL instead of total harvested wood. Consequently, harvested amount of SVL is compared with SVL demand. In the second bloc of the algorithm the allowable amount of harvested wood of the other assortments is estimated. The first step is to check whether the estimated amount o other wood assortments fulfills the demand or not. If it does not fulfill then additional felling is performed in the managed forest. Fulfilling the demand of SVL s checked as well.

The improved forest management algorithm for geospatial global model G4M considers assortment structue of a forest stand for simulation of harvest. In case of Ukraine, the differentiation of the assortment structure reduced the difference between deman and harvested wood assortments to less than 1%. The proposed algorithm takes into account the aggregated distribution of assortments, such as SVL and othr assortments of wood. The algorithm is designed in a way that additional allocation of assortments is technically easy to implement. The improvements interven minimally in the existing modules of G4M, preventing unplanned change of existing logic of the program.